To focus on the future of your product you can archive release, its sprints, and backlog items. Archived items are not loaded in BACKLOG, PLAN or WORK views. This will significantly increase performance as well.
Archived items are still available in REPORTS and DOCUMENTS so you can check what was planned previously. This is a difference comparing to other popular application which does not provide such information easily.
If your product owner still needs to see what happen in history, archived releases can be displayed inPLAN view by click on the checkbox Show archived releases. Archived releases are displayed with gray pattern.
To archive release, click it and then click icon in the details page.